Archaeological Sites After Disasters

Good morning. My name is Tad Britt. I’m Chief of Archaeology and Collections for the National Center for Preservation Technology and Training, and today I’d like to talk about archaeological sites after disasters, documentation, and planning.

Before we get started, I’d like to tell about NCPTT’s mission. NCPTT advances the application of science and technology to historic preservation. Working in the fields of archaeology, architecture, landscape architecture and materials conservation, the Center accomplishes its mission through training, education, research, technology transfer and partnerships. The NCPTT promotes excellence in preservation by promoting and developing educational opportunities for professionals. This includes nationwide seminars and workshops on topics like green building science and nondestructive archaeology.

The focus of this session is to prepare the audience for what impacts may occur to archaeological sites as a result of a natural or human-made disaster. Today we’ll discuss the effects caused by wind, water, fire and a combination thereof. In addition, we’ll also take a look at the BP “Horizon” oil spill and the innovative approach for documenting resources. This webinar focuses on natural and human-induced catastrophes, field documentation techniques, mitigation, and appropriate response strategies depending on the type and extent of the event.

A natural disaster is a major adverse event resulting from natural processes of the earth. Examples include floods, drought, hurricanes, tsunami, and other geologic processes. A natural disaster can cause loss of life or property damage, and typically leaves economic damage in its wake.

First, let’s talk about wind. Whether it’s a tornado or hurricane, these natural phenomena can cause untold damage to archaeological sites. Ripping through and shredding sites across the landscape are often the most common effects rendered by these storms.

Depending on the cultural resources affected, these effects can totally obliterate a site or expose them for the first time. The archaeologist in the field must be prepared to capture and preserve what data is available. This could range from documenting the destruction of the site or taking immediate mitigative action to stabilize the site for later documentation.

Perhaps the most destructive physical impact is wind-blown overturned trees. Since the majority of the primary root systems of most trees is within the first few feet below the surface of the ground, blow-downs are likely to pull large clumps of soil and artifacts from an archaeological deposit. As Ian Brown noted, Hurricane Ivan in 2004 and Katrina in 2005 inflicted damage on sites across the northern Gulf Coast, even harming excavated collections stored in facilities inundated by storm surges.

Next we’ll talk about water. Water damage comes in a variety of manners and also can run the gamut of total destruction to the uncovering and exposure of new sites. Rain, flooding, hurricanes and tsunamis often occur in combination and can be very devastating.

Most recently I was deployed to work in New York and New Jersey following Superstorm Sandy. Pictured here is a previously unknown and undocumented gun battery at Fort Wadsworth, New York. The storm surge exposed this important beachfront cultural resource. It’s unique architecturally, and that is the only hand-cut granite arch battery at the Fort.

Additional documentation was recommended to completely inventory and evaluate the National Register of Historic Places of Significance for this structure. It is also important to note that archaeological sites that may or may not have been affected by either natural or man-made disasters could very possibly be adversely affected by post-event actions such as clearing of debris, staging areas, et cetera.

Now we’ll discuss tsunamis. I was deployed to American Samoa following the 2009 tsunami and was part of an engineering forensics team. Our purpose was to document the devastation and to develop a mitigation plan. The National Park System of American Samoa reported that four tsunami waves, 15 to 20 feet high, hit American Samoa shortly after the earthquake. The water flowed inland about 100 yards before receding.

What we’re seeing here is the beach erosion effects following the American Samoa tsunami. As the photo depicts, beach erosion almost compromised the roadway and left the palm tree root system exposed along the road. Before we discuss the cemeteries at Kalaupapa, I think it’s important to note when Hansen’s Disease was introduced to the Hawaiian Islands, King Kamehameha banished all afflicted to the Island of Kalaupapa Peninsula on the north shore of Molokai.

Since 1866, more than 8,000 people, mostly Hawaiiians, have died at Kalaupapa. Once a virtual prison, Kalaupapa is now a refuge for the few remaining residents who are now cured but were once forced to live their lives in isolation. The cumulative effects over time at this cemetery have been affected by a combination of a tsunami as well as wind-borne sand and salt erosion. The Park has done an amazing job of rehabilitating some of the grave markers, and the NCPTT is currently consulting with the Park to develop a preservation plan for their cemeteries.

Now I’d like to shift gears to a new type of disaster, drought. Severe drought often exposes previously inundated cultural resources. This is the silver lining in a dark cloud. This turn of the 20th century watercraft was abandoned along a tributary to the Pearl River in Southeast Mississippi. This particular boat was designed especially for the narrow, meandering tributaries of the Pearl River. It was an early gasoline-powered rear paddle wheeler. The sternwheeler was deemed eligible for listing in the National Register and was mitigated by mapping, drawing and written documentation.

Another drought-related exposure, an early 20th century pine raft. These were virgin pine logs held together with dogs. Typically these were cut, formed into rafts, and floated down the Pearl River to the lumber mills. This, too, was documented and deemed significant within the historic context of logging activities along the lower Pearl River.

Now I’d like to talk about some of the negative effects of fire on archaeological sites. You get increased visibility from vegetation burn-off and, consequently, greater vulnerability to vandalism. You get physical damage to sites from snags and trees falling. There’s soil erosion and the loss of archaeological data. There’s increased damage from rain, new drainage patterns and flooding. And there’s also increased rodent and insect activity within the soil matrix.

Now we’ll talk about the effects caused by direct impact. Fire can consume flammable materials and accelerate oxidation of metal, melt glass, and get up to 500 degrees centigrade, which can totally devastate an archaeological site. Some of the indirect effects of post-fire habitat include decreased soil moisture, increased light, increased wind, increased temperature extremes, sometimes creating more diversity, sometimes regeneration. Usually the higher the burn severity the greater the community changes will be. This could be a nutrient flush, some plants will grow more robustly and prolifically, unfortunately, including exotics, and sometimes the soil is sterilized and the soil will remain barren and susceptible to erosion from wind and water. And, finally exposure of cultural resources may be more vulnerable to theft.

Shifting gears again, now we’ll talk about the oil spill. In response to the BP “Horizon” oil spill, BP deployed archaeologists to survey and document existing and newly exposed archaeological sites. Some of the archaeologists’ concerns were that the sites would be damaged by the oil or subjected to erosion following clean-up efforts. Over 100 sites were visited. Monitoring during the cleanup was conducted, and samples for analysis and radiocarbon dating were collected.

Shown here are a variety of cultural resource sites that could have been affected by the oil spill. Fortunately, only Texas to Florida were affected by the spill. There was some concern early on that the wind and currents could have carried the oil up and along Florida’s East Coast.

Now we’ll talk about documentation. Archaeological documentation can be carried out only after defining explicit goals and a methodology for reaching them. The goals of the documentation effort directly reflect the goals of the preservation plan and the specific needs identified for the relevant historic context. In the case of problem-oriented archaeological research, the plan usually takes the form of a formal research design and includes, in addition to the items listed below, explicit statements of the problem to be addressed and the methods or tests to be applied.

The purpose of the statement of objectives is to explain the rationale behind the documentation effort, to define the scope of the investigation, to identify the methods, techniques and procedures to be used, to provide a schedule for the activities, and to permit comparison of the proposed research with the results. The research designed for an archaeological documentation effort follows the same guidelines as those for identification but has more property-specific orientation.

The research design should draw upon the preservation plan to identify evaluated significance of the properties to be studied, research problems or other issues relevant to the significance of the property, prior research on the topic and property type, and how the proposed documentation efforts are related to previous research and existing knowledge, the amount and kind of information required to address the documentation objectives, and to make reliable statements, including at what point information is redundant and documentations have reached a point of diminishing returns, methods to be used to find the information, and finally, relationships of the proposed archaeological investigations to anticipated historical or structural documentation or other treatments.

Now I’d like to talk about an emergent data collection system known as the OMNi, which stands for Observational Mapping and Noting Instrument. It’s an innovative technology designed and developed through a cooperative research and development agreement between the U.S. Army Corps of Engineers and Compass Systems, an engineering firm. Originally developed to record archaeological sites, it now has been adapted by forensic engineers and the U.S. Army for reconnaissance missions.

The OMNi device allows the user to collect precise georeference intelligence while tagging the GPS location with voice, photo, audio, video, environmental data and text notes. It is lightweight, very portable, and can be used from land, sea or air to safely capture specific target coordinates from a stand-off position up to a thousand meters. The information is then posted immediately to Google Earth for analysis and action.

This real-time sharing of intelligence allows multiple agencies to respond rapidly while coordinating and streamlining clean-up and restoration efforts. The benefits of this technology is that it reduces human error and eliminates redundancy of transcription, it documents digitally, accurately and consistently, it generates a georeferenced baseline metric for change detection, it provides a secure chain of custody on all the data, metadata, it serves as a mobile desktop GIS, it allows an on-the-fly processing and analysis, it provides objective data for stakeholder consultation, and it provides an automated report generation and dissemination via wi-fi.

Utilizing the OMNi technology…

It’s to rapidly capture shoreline assessment data along the Gulf Coast following the BP oil spill. We utilized this data to quickly generate a Google Earth interface to present this data by generating standard NOAA forms. It integrates additional multimedia, pictures, video, audio, and field samples can be collected, cataloged and bar coded. The OMNi has a variety of uses and can be adapted to document archaeological sites as well as environmental data.

Here we are using the OMNi to survey and map tar balls at Gulf Island National Seashore. Now for documentation…These ArcPad forms were prepared for documenting cultural resources and used at Catalina Island, California, following a brushfire that consumed much of the island in 2007.

The form flow is intuitive and logic driven, and the ArcPad form categories are objective and allow the user to select buttons from drop-down menus. Onboard references such as user reference manuals, photos, PDFs, Word files can all be integrated via hot links.

ArcPad has the ability to categorize and summarize events in the field for rapid assessments if required. Now we’re talking about archaeological site recordation. This depicts the thoroughness, order and complexity of the program. ArcPad may be programmed so that user cannot advance to the next screen unless all data boxes have been checked.

This ensures consistent, complete data acquisition across the board. All data is time/date stamped. Note the comments screen to add notes about events not anticipated. ArcPad can also be programmed in the field should the user encounter a feature not included on the customized form. This is called the Feature on the Fly. Utilizing ArcPad, we developed an historic building app for survey of an historic district is Champagne, Illinois. Again, you can see how the drop-down menus, radio buttons guide the user through the documentation process.

Now we’ll talk about mitigation. An archaeological mitigation strategy is a statement of recommendations for reducing the overall effect of an undertaking on archaeological remains. The strategy will normally consist of one or more of the following: preservation in place, modifications to the development design proposal, excavation, or archaeological monitoring.

Now we’ll talk briefly about the Section 106 process. You initiate the process by establishing the undertaking, identify the appropriate SHPOs and TPOs, plan to involve the public and also identify other consulting parties. The next step is to identify historic properties, determine the scope of the effort, identify historic properties and evaluate historic significance. The step after that is that historic properties are affected, so assess adverse effects. So you apply the criteria for adverse effects. Then if the historic properties are adversely affected, you resolve adverse effects through an MOA, or on failure to agree, it goes to the Advisory Council on Historic Preservation for a recommendation.

Now we’ll talk about mitigation, specifically geotextile mitigation. Filter fabrics have been available for many years. These materials are produced both as woven and non-woven fabrics and are available in varying weights and porosities. These materials, regardless of manufacturer, are relatively inert geosynthetics that are resistant to ultraviolet degeneration. The advantages of this geotextile cloth are as stabilizing material. The filter fabrics offer a number of advantages for an archaeological application. Most have sufficient elasticity to allow them to be molded to the regular surface contours that characterize archaeological sites without massive surface preparation. The relatively lightweight of the material makes it easy to handle and install on horizontal sloping and vertical surfaces. Since the fabric is a synthetic, it is resistant to wave, rain and surface water erosion, and the permeability of the materials can be controlled to some degree by careful fabric selection. Once in place, the fabric will add surface strength to an archaeological deposit, and as a result, slope stability is improved. At the same time, growth or surface vegetation can be encouraged or discouraged by selecting a material of appropriate weave, weight or porosity.

The disadvantage of geotextiles is that the single greatest disadvantage is that they all have a finite use life. To ensure that the maximum protection is realized, every installation must be inspected regularly and either maintained or replaced. One of these materials also requires that some additional stabilization measures be identified and put into place before the useful life of the initial installation is reached or exceeded.

Now we’ll talk about revegetation. Archaeological sites throughout much of the United States have been covered with some form of vegetation since they were abandoned by their original inhabitants. Carefully planned revegetation of such a site will not constitute a previously unknown intrusion into the cultural deposit. Such major earthworks such as those at Cahokia, Emerald, the Pharr Mounds on the Natchez Trace and the Great Serpent Mound have been maintained through the use of floral cover.

At the Winterville Mounds depicted here, dense strands of tall grass have been used for several years to stabilize the sides of the mounds as well as to direct the movement of visitors around the park. The benefits of revegetation is that the reintroduction of plants on or around an archaeological site can be one of the least visually intrusive stabilization techniques available. Careful species selection produces a vegetative cover that blends well with the surrounding environment and places a site in a more natural setting.

The use of vegetation as a means of achieving site stability can be viewed as a soft approach. Plant systems have the advantage of being elastic, and species easily can be found. They’re adapted to a broad range of microtopographic settings. Vegetation can also effectively dissipate wind and water energy that can destroy a cultural deposit. Also, the destructive force of various forms of erosion can be lessened, if not completely stopped, in many situations through the use of carefully selected vegetation. As the lateral roots or vegetation spread and intermingle, the soils become bound together and act like a composite material. Stresses in the soil are transferred to the root fibers, which have relatively high tensile strength, and in this manner, the soil is reinforced and strengthened.

In conclusion, the importance of integrating historic property and cultural resource considerations into mitigation planning has been made all too apparent in disasters that have occurred recently such as Hurricane Katrina and Superstorm Sandy. Whether disaster impacts a major community museum, an historic main street or an archaeological site, the sudden loss of cultural resources can negatively impact a community’s character and economy, and it can also affect the overall ability of the community to recover from a disaster.

This How-To Guide Number 6, otherwise known as FEMA 386-6, shows communities step by step with the needed tools and resources how to develop and then implement a pre-disaster planning strategy for historic properties and cultural resources.

Basically you need to organize resources, assess risk, develop a mitigation plan, and implement the plan and monitor progress.

And before I take questions, I’d like to thank Sara Jackson at NCPTT for organizing this webinar and also Steve Floray and Gene Kinoshita, National Park Service, who graciously lent me some of their photos, the Army Corps of Engineers, Compass Systems, Dr. Robert Thorne, and lastly, the National Park Service.